A great circle crosses the equator at 173°E. It will also cross the equator at what other longitude?

Correct Answer: Option C — 7°W

Great circles are symmetrical tracks on the globe. An intersection with the equator at a given longitude has its antipodal point exactly 180° away. For 173°E, the opposite longitude is 180° - 173° = 7°W, which is the other equatorial crossing point per Bowditch principles.